The theme of policeman and criminal forming a mutual admiration society has long been a popular one in cinema. Outstanding examples can be found in France (Le Samourai, d. Jean-Pierre Melville, 1967), Hong Kong (The Killer, d. John Woo, 1989) and the US (Heat, d. Michael Mann, 1995) - and The Spider and the Fly (d. Robert Hamer, 1949), though considerably less well known, is in a very similar vein.

Inevitably overshadowed by Hamer's other film that year, his masterpiece Kind Hearts and Coronets, The Spider and the Fly is a low-key but expertly-staged little thriller, set in France just before and during World War I. Inspector Fernand Maubert (Eric Portman) is plagued by inept functionaries and blustering politicians.

He is far more impressed by the safecracker Philippe de Ledocq (Guy Rolfe), a man whose dedication to his craft fully matches Maubert's (not to mention his impatience with careless henchmen), despite him operating on the wrong side of the law. But Maubert is convinced that this can be changed, given the right circumstances - such as a vital espionage job for the French government.

Portman had spent the past decade specialising in driven obsessives, most notably in A Canterbury Tale (d. Powell & Pressburger, 1944) and Dear Murderer (d. Arthur Crabtree, 1947), and is perfectly cast as the intense, perfectionist Maubert. More surprisingly, the tall, saturnine Rolfe is comfortably his match as Ledocq, an impressive achievement given that he had only recently graduated from uncredited bit parts in Nicholas Nickleby (d. Cavalcanti, 1947) and Odd Man Out (d. Carol Reed, 1947) - this was only his third leading role.

Hamer stages all this with considerable wit, elegance and economy, and includes two gripping suspense sequences as Ledocq demonstrates his cat-burgling skills at considerable personal peril. Less successful is the romantic subplot involving Madeleine (Nadia Gray) - although she's linked to both men, it's clear they're ultimately more interested in each other, and her eventual fate is oddly muted considering the underlying irony.

Although the foreground characters speak English, the French atmosphere is caught surprisingly effectively for a British studio film of its era, presumably courtesy of 'French Adviser' Jacques Brunius, a former assistant to the great French film-maker Jean Renoir.